Wireless Local Area Networks (WLANS) have become ubiquitous. Typically, a single channel is used for wireless communication in WLANs, which is accessed through, among others, a distributed MAC protocol. [IEEE 802.11 standard] WLANS can include multiple channels and multiple radios. An approach that offers both multi-channel and multi-radio capabilities appears in the co-pending patent application titled “A Protocol For Wireless Multi-Channel Access Control”, filed Mar. 29, 2006, the disclosure of which is incorporated by reference herein, which describes the CCC (Common Control Channel) MAC protocol. CCC utilizes two types of logical channels, the control channel and the data channels.
In wireless Local Area Networks (LANS), a wireless channel can be reserved for the transmission of a sequence of frames while employing asynchronous distributed random channel access methods. In such an environment, both the source and destination of the transmission broadcast the reservation duration in order to establish the interference neighborhood.
According to the 802.11 distributed channel access MAC protocol, RTS/CTS frames are used to notify neighbors of a transmission. The source and destination of the transmission send the RTS and CTS control frames, respectively, which contain the reservation duration in order to establish the interference neighborhood. Nodes receiving either control frame refrain from transmitting or agreeing to receive a transmission for the specified duration.
Growth in demand for Wireless Local Area Networks (WLANs) is driving the development of new technology to provide higher throughput. To a greater extent this growth is due to the increased number of users and applications desiring wireless transmission and to a lesser extent to the emergence of new applications needing higher transmission rates along a single connection between two points. Previous work has focused on increasing link throughput. This is necessary for single-stream high throughput applications. While it helps increase aggregate throughput, it is not the only way to do so. A MAC-based approach that enables the parallel use of multiple channels in a BSS, or a wireless mesh, can increase aggregate throughput.
IEEE 802.11 has been allocated multiple non-overlapping channels. (i.e., 3 channels are available in the 2.4 GHz ISM RF band for 802.11b/g and 12 channels in the 5 GHz U-NII RF band for 802.11a). These channels can be used simultaneously, if the transmitter on one channel and the receiver on the other have sufficient separation between them to render negligible any interference (referred to as adjacent channel interference or ACI) that would result from energy from the transmitter side lobes spreading out across the spectrum onto the other channel. When co-locating multiple radios in the same station, the interference arising when a station receives and transmits simultaneously on adjacent (in the RF spectrum) channels is so high that it blocks reception. Multiple radios are useful in increasing node-processing rates in stations where high traffic concentration is expected.